The organic light-emitting layer of an organic electroluminescent device OLED is prepared mainly by using a fully fluorescent material, a fully phosphorescent material, or a mixture of fluorescent material and phosphorescent material. The fluorescent light-emitting material in the prior art is prone to fluorescent quenching, and the device prepared by doping the light-emitting layer with the fluorescent light-emitting material in the prior art is prone to crystallization phenomenon, which leads to reduced service life. And it is difficult to use a phosphorescent light-emitting material to synthesize a stable dark-blue light material.
In order to solve the above-mentioned problem, cationic complex is developed to be used as light-emitting material. The synthesis conditions of this type of material are mild and easy to carry out, with high yield, and the product is simple to purify; secondly, this type of complex has good redox properties and can increase the stability of the device. However, because ionic material has poor volatilization properties and is not suitable for preparing a device by means of evaporation-deposition, which severely limits the use of this type of material in electronic devices.
Advanced Functional Materials, 2007, 17, 315 discloses an Iridium complex having a structure shown in the following formula (41), wherein the reported two kinds of depositable ionic complexes adopt an Iridium complex as the cation, and adopts a hexafluorophosphate anion as the counterion. This method has a deficiency of not having universality, i.e. more kinds of depositable ionic complexes cannot be developed according to this route.
